We fit both, and we have no preference, so here is the straight comparison we give customers at the quote stage.
Cost and time
Panelling is normally quicker to install, which reduces labour. Tiling takes longer, especially with large-format or patterned tiles, but tile prices vary so much that the material cost can go either way.
Maintenance
Panels have no grout lines, so nothing to scrub or discolour. Grout can be sealed and cleaned, but in a heavily used family shower it will eventually need attention.
Tiles are easier to repair in isolation, one cracked tile can be replaced, whereas a damaged panel usually means replacing the sheet.
The look
Tiles still give the most convincing high-end finish, particularly natural stone and marble effects with narrow grout joints. Modern panels have come a long way, though, and in a shower enclosure most people cannot tell.
Plenty of the rooms we fit use both: panelling inside the shower, tiling elsewhere.